Pin joints for machinery generally fall into two categories. Dynamic joints where structural members move relative to each other and static joints where the structural members do not move. When dynamic joints are present, they may move back and forth making oscillatory motion. In some instances, this can create friction and wear that may limit the life of the pin joint. Consequently, the art has developed schemes to limit this friction and prolong the life of the pin joint.
Self-lubricating bearings have been developed to eliminate the need for wet lubricant in the pin joints, however there are no reliable sealing systems available to protect these bearings. Grease lip seals that comprise a steel can or backbone that supports a single urethane lip to protect the pin-to-bearing interface have also been developed. However, these seals are not designed for performance and long life in the absence of a lubricant. This may lead to failure of the pin joint and unplanned downtime of the machine.
Therefore, it is desirable to develop a better seal system for use with self-lubricating bearings in a dynamic pin joint for machinery.